The large recall, triggered when the bacterium Listeria monocytogenes were detected at a processing plant, has stores across the country (including Trader Joe’s and Whole Foods Market) pulling “tons of ready-to-eat and ready-to-cook foods” off their shelves, WebMD reported Thursday.

Elderly people, pregnant women and individuals with weakened immune systems are most at risk of serious illness from listeria infection, according to this website from the Centers for Disease Control and Prevention. Listeriosis can cause fever, muscle aches and diarrhea, as well as miscarriage. There are about 1,600 cases each year in the U.S.

One bright spot in the onion recall: No one has been sickened by tainted onions, and only one bag of onions has tested positive for listeria, Gill’s said on its website. According to CDC reports, a listeria outbreak in 2011 — which originated in cantaloupes from Colorado’s Jensen Farms and spread through 28 states across the U.S. — infected 146 people, killing 30 and possibly causing a miscarriage in a pregnant woman who fell ill.